A STA accesses, by associating with an access point (AP), a wireless local area network (WLAN) controller that manages the AP.
The STA may be handed over between different WLAN controllers by associating with APs managed by the different WLAN controllers, and this manner is referred to as roaming of the STA between WLAN controllers. Multiple WLAN controllers may communicate with each other, and the multiple WLAN controllers may form, in a network, a single system with a particular function, where the system may be referred to as a WLAN controller cluster. As shown in FIG. 1, a service device may be independently disposed in a WLAN controller cluster, to manage WLAN controllers in the WLAN controller cluster, where the independently disposed service device is referred to as a cluster server. Alternatively, there may be no cluster server disposed in the WLAN controller cluster.
When a STA is handed over in a WLAN controller cluster, authentication data of the STA needs to be synchronized between WLAN controllers before and after the handover. A scenario in which a cluster server is disposed, the authentication data of the STA needs to be synchronized to the cluster server in advance such that when the STA associates with an AP managed by a different WLAN controller, the STA does not need to be authenticated repeatedly. The authentication data of the STA includes a media access control (MAC) address of the STA, a pairwise master key (PMK) between the STA and an AP associated with the STA, an identifier of a WLAN controller that manages the AP associated with the STA, and the like.
Generally, a WLAN controller that manages an AP currently associated with an STA sends authentication data of the STA to other WLAN controllers in a WLAN controller cluster when the STA associates with the AP, or in a scenario in which a cluster server is disposed, the authentication data of the STA needs to be synchronized to the cluster server. As a quantity of STAs increases, an amount of signaling required by processing when a WLAN controller synchronizes authentication data of the STAs also increases correspondingly, which greatly affects performance of an entire system.